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Session Border Controllers Evolving to Support Video Conferencing

(Rebecca Wetzel of NetForecast contributed to this item)

We are on the cusp of a leap forward in the ability of session border controllers (SBCs) to support real-time, business-to-business (B2B) video conferencing and telepresence in addition to VoIP. An SBC's job is to control the signaling and media streams needed to set up, conduct, and end telephone calls--and other forms of interactive media "calls". We recently interviewed four SBC vendors to gather their views on the issues and time line for SBCs to support video conferencing "calls" in the same flexible way they support VoIP today. The upshot is that supporting video conferencing is complex, but they are working on it and plan to be ready when B2B videoconferencing catches on.

We interviewed representatives from Metaswitch, Acme Packet, Edgewater Networks, and Ingate. Tori Downes of Metaswitch told us of their support for video conferencing: "We are implementing now for deployment soon." Tori’s view is that customers are not yet clamoring for B2B video conferencing support, but she thinks the demand is growing, and believes Metaswitch's SBC lineup will be ready for the anticipated need.

Video conferencing traffic behavior and requirements are more complex and place more demands on the network than VoIP.

In contrast to a single stream per voice call, video conferencing sessions can involve two or three streams delivering a mix of video, audio, and data. There are issues of conference registration and virtual room creation, far-end camera and presenter control, NAT firewall traversal, and QoS--and transcoding is often required to convert from one video format to another. Also, video conferencing is bandwidth intensive, and to prevent video traffic from consuming more bandwidth than needed, video flow rates should be configurable across the network to match the destination data rate near the source in a process called trans-rating.

This long list of functions can, and in some cases will, live within an SBC.

Typical of new technologies, video conferencing vendors use a plethora of solutions and standards that do not interoperate. This is a problem and an opportunity for SBC vendors, who can turn their devices into havens of interoperability, for example between H.323 and SIP protocols. This interoperability is especially important in environments that support end points using many vendor solutions.

Standards bodies like the SIP Forum are working to drive commonality, but Ingate’s Steve Johnson, a SIP Forum member, warns that if these efforts drag, "it will be the Wild West for a long time." Given the slow speed with which standards bodies historically operate and markets gravitate to standards, SBC vendors who can offer interoperability may be ahead of the game in multivendor environments.

SBC vendors who aim to support the emerging market for inter-enterprise video conferencing and video conferencing within enterprises sporting multi-vendor video conferencing deployments should be working overtime to build features that will make life easy for customers. Vendors serving enterprises with homogeneous video conferencing solutions need not peddle hard to support a variety of scenarios.

Jonathan Zarkower of Acme Packet predicts that due to the innate complexity of video conferencing: “Hosted service providers will play a bigger role for video than they did for voice. We will see network-based services to facilitate interworking, and also federating to manage bandwidth use, integrate presence, and match the right pipes with bandwidth requirements.”

So stay tuned--innovation is afoot among SBC vendors who support video conferencing.